Well I finally was able to play again thanks to the J version.
I don't really know exactly what is going on, but in that same dungeon; even if in an older version it appears now they just don't build the bridges in that area.
I was wrong in it being in north east, it is south east of that map.
The one that is finished, was the original spot that I had to put dirt down first to get rid of the reeds, then placed that order to build it. Only then would that one that you see built gets built.
Now with the other two you see in process of being built, the one on the bottom with 1 string left was the second one I laid down to test, and this is over another batch of reeds that I was talking about in the other post.
However instead of doing what it did before, which was they built and then it disappears when done building leaving materials on shore; this time it appears they don't want to even attempt to build there. So I even laid down the third one top see if that was the case, and that one is not over reeds; it is over clear water.
so I think it may be a bit more than meets the eye on this one. It seems to be only that particular area of water it does this. I have setup of building ques elsewhere and they immediately go, build, and finish the project. These ones I have yet to see them finish in all 3 hours I watched them. Imps seem to go to it then walk back with rope in their hands as if they found it on ground, sometimes stopping short distance from the "work in progress" bridges, and turning back.
Now I don't even really know what is going on, or if it is somewhat just the fact it being started in older version or the bug manifesting in a different way. Can't seem to pin point the exact nature of it.
Also note When I first loaded the map the day before it crashed when it got to the bridge building part, and then crashed a second time deleting the file. Good thing I have a back up; even though I had to redo the newly implemented stuff again. Laying beds for 2 of the creatures, one needed for the cookery, and the other I just had complaints from due to lack of bed. And fixing the production links a bit so it was manageable with out worries much. So after all that, on the next day I got to what I described above with the bridges.
Seems like an overly long endless routine that seems to not ever finish for some reason, when else where in the dungeon I can get them to construct things. I can get them to dig in the area no problems it is just building a wooden bridge in the area that for some reason they are not finishing in timely manner. 2-3 hours for a bridge is a bit much, and the reason I knew it was like that is building a bridge in another water hole they finished it within minutes like a hoard to drop materials and one to construct it.
If you want the error log for the crash I mentioned I attatched it. Although I think that was mainly due to the memory problems I was having with my computer that day. As I did all my actual testing those bridges on the next day when I somewhat solved my memory issue. I only ran the debug on the first crash and not the time it corrupted on save which left a 0 byte file. didn't even start saving.
This is the file being used in the J2 version it is now:
https://www.dropbox.com/s/efjbb5bftrs7p4...3.dat?dl=0
Anyway I hope this helps a little at least with what I thought was originally the problem; might be something else entirely, but is specific to that location.
EDIT: I just noticed in the screen shot it reset the material cost. I'll have to check this out shortly...